Collet



Patented Jan. .25, 1949 COLLET Arthur Merrick Stoner, West Hartford; Conn, as-

signor to The Jacobs Manufacturing Company, Hartford, Conn, a corporation of Connecticut Application February 4, 1944, Serial No. 521,097

'7 Claims. (01. 279-41) This invention relates to improvements in collets of the type in which angularly spaced rigid gripping members are interconnected by resilient material which maintains the gripping members in desired relative positions but permits them to be displaced inwardly and outwardly. A collet of this class is described in my U. S. Patent No. 2,346,706, issued April 18, 1944. The'range of adjustability of a collet constructed as described therein is limited to such an extent that it has been necessary to furnish a set of several collets for each chuck to adapt the chuck to the full range of tool or stock sizes within its capacity. The principal object of the present invention is to provide an improved'collet which is adjustable over the entire range of sizes within the chuck capacity, to avoid the necessity of providing several collets for a given chuck. I

In a collet constructed according to the aforesaid patent, adjacent sides of proximate gripping members are nearly parallel and, if extended, would meet at an acute angle, or are otherwise so shaped that the resilient material between them, when displaced by inward movement of the gripping members, bulges inwardly and outwardly like a block axially loadedwith little or no tendency to buckle inone direction. Such of the resilient material as becomes displaced inwardly becomes interposed betweenthe inner edges of the gripping members andlimits their inward radial movement. 7

According to the present invention, the adjacent sides of proximate grippin members and the resilient material between themare sorelated to each other that the resilient material forms, in effect, columns upon which theoutward lateral load imposed by the inward movement of the gripping members is greater than the inward lateral load thereon, so that these columns buckle or fold outwardly away fromthe inner edges of the gripping members when the gripping members are moved radially inwardly.

Another object is to so form the resilient material relative to the space within the chuck that the buckling columns have ample room in which to buckle, permitting full range of adj'ustability of the gripping members for all tool or stock sizes within the capacity of the chuck.

Another object is to proportion and arrange the resilient material in relation to the spaces between adjacent sides of proximate gripping members so that it is caused to fold upon itself as the space between adjacent gripping members is decreased by the inward displacement of the latter. Other objects of the invention will Jap- 2 pear in the following specification in which I will describe certain embodiments of the invention, the novel features of which will be set forth in the appended claims.

Referring to the drawings:

Figure 1 is a side elevation and Fig. 2 a front view of a collet which is made according to and embodies the present invention. In these figures the gripping members are in the relative positions which they assume when the resilient,

wardly to the maximum extent and the resilient material forced outwardly and foldedupon itself between them. 7

Figs. 6, 7 and 8 are sectional front elevations,

similar to Fig. 2, illustrating structural modifilations;

. Fig. 9 is a sectional side elevation of a chuck, of which a collet such as that shown in Figs. 1 and 2 is a part. In this figure the parts of the chuck are in their open or unclamping position.

Fig. 10 is a similar view of a chuck of modified construction with its parts closed or tightened against a collet with its gripping members moved together against an article of small diameter. Figs. 9 and 10 are included to illustrate ways in which this improved collet maybe used.

Inall of the figures of the drawings '20 desigates the rigid clamping members. the particular form shown, are flat metallic plates. beveled to fonn inner straight gripping edges 2! which are chamfered at their outer endsas at 22 to facilitate the insertion of a desired article, such as the shank of a tool. A part 23 of their outer edges is inclined to extend to a conical cam surface of a chuck. The rear outer edges 24 are parallel with the gripping edges 2!. The rear ends 25 are at right angles to the gripping edges. ably with transverse orifices 26.

30 designates a body of resilient material which maybe bonded to the sides of the gripping members and extends from each member to the adjacent ones. Oil resistant synthetic rubber is a suitable materialto use for this purpose. When the plates are provided with the orifices '26, the

These, in

These plates are provided preferresilient material passes through them. The front edge 3| of the body of resilient material is spaced from the front ends of the gripping members and its rear edge 32 is spaced from the rear ends of these members. In the specific construction shown in Figs. 1 and 2, its outer surfaces 33 are flat and are spaced from and parallel with the inclined outer edges 23 of the gripping members (see Fig. 1). The rear portions 34 extend to the edges 24 of the gripping members. As shown in Figs. 2, 4 and '7, its inner sure faces lie in a cylinder spaced inwardly from and parallel with the inner edges 2! of the grip ping members.

The resilient material is molded or otherwise formed so that when it is in its normal condition it holds the gripping members in substantially radial positions, equally spaced angularly with the distance between their inner edges 2| somewhat less than anarticle of maximum diend of which is adapted to be afiixed to the spindle of a machine tool. The body is constructed to form a hollow portion ll with a cylindrical bore 42,. the forward part of which is internally threaded as at 43. 44 is a block longitudinally slidable in the bore 12. The front end of this block is a flat transverse surface designated by 45. 46 is a transverse pin which passes through and is rotatable in the block. The pin hasenlarged heads 47 which are eccentric to the axis of rotation of thepin and are seated in circular holes in the body 46. 48 is an externally threaded collar which engages the threads 43 on the body. This collar has an internal cone shaped cam surface 49. The collet is placed in the chuck back of thecollar 48 with the rear ends 25 of its gripping members seated on the surfac of the block 44. a

When an article suchas that shown at A in Fig. 4 is thrust into the collet the'gripping members are forced outwardly and the resilient material is stretched and placed under tension. The result is that the article will be held by the gripping members even when the axis of the chuck is in a vertical position.

When the collar 48 is screwed into the body 46 its cam surface 29 will move the g'ripping members into engagement with anything which is between them. They can be further tightened by rotating the pin 36 to, move the block 44 and the gripping members forwardly. I

The angularity between the sides of adjacent gripping members is made sufi'iciently large as to cause outward displacement of the resilient body during the inward displacement of the gripping members and to fold the resilient body outwardly upon itself in the spaces between the grippin members and the conical cam surface.

In Fig. 6 the inner surfaces 35A of the resilient material are flat, as are its outer surfaces 34.

Another modification is shown in Fig. 7 in which the inner surfaces 35 of the resilient material are segments of a cylinder as in Fig. 2, but its outer surfaces 34A are concaved.

A still further modification is illustrated in Fig. 8 in'which both the outer and inner surfaces 343 and 35B, of the resilient material are convex.

'Various modifications in construction, mode of operation, method and use of an invention may 7 and do occur to others, especially after benefit- The chuck shown in Fig. 19 has a body 40A cular holes in the sleeve 44A. The sleeve 44A and the collar 48 may be drawn back by rotating the pin. V

ting from knowledge of such a disclosure as that herein presented of the principles involved, but the invention itself is not confined to the present showing.

Having thus described the invention, what is claimed is:

15A collet of wide range for a machine tool chuck having an internal conical cam surface, said collet, comprising aplurality of tapered angularly v spaced rigid gripping members symmetrically disposed about the axis of the cam surface, said gripping members being arranged to extend to and be engaged by the cam surface and being movable radially in concert toward and away from said axis whereby the volume of the spaces between them is varied, non-compressible struts of resilient material in said spaces based upon adjacent sides of proximate gripping members and connected to said members, the outer surfaces of' said struts being spaced from the cam surface to provide clearances into which the struts may fold,,and means including the stints for inducing outward folding of said struts upon: axial loading thereof when said gripping members are moved radially inwardly,

2. A collet of wide range for a machine tool chuck having an internal conical cam surface,

, said collet, comprising a plurality of tapered angularly spaced rigid gripping members symmetrically disposed about the axis of the cam surface, said grippin members being arranged to eXtend'to and be engaged by the cam surface and being movable radially iniconcert toward and away from said axis whereby the volume of the spaces between themis varied with adjacent sides of proximate gripping members forming outwardly flaring angles to one another, and noncompressible struts of resilient material in said spaces based upon said adjacent sides of proximate gripping members and connected to said members, the outer surfaces'of said struts being spaced from the cam surface to provide clearancesinto which the struts may fold, with the angularity between the opposite bases of each strut forming means for causing an outward lateral pressure to be exerted upon the struts by inward movement of the gripping members in excess or the innerlateral pressure thereon, whereby the struts are folded outwardly.

3. A collet of wide range for a machine tool chuck having an internal conical'cam surface, said collet comprising'aplurality of tapered angularly spaced rigid gripping members symmetrically disposed about the axis of the cam surface, said grippin 'members being arranged to extend to and be engaged by the cam surface andbeing movable radially in concert toward and away from said axis whereby the volume of the spaces between them is varied, with adjacent sides of proximate gripping members forming outwardly flaring angles to one another, and non-compressible struts of resilient material in said spaces based upon said adjacent. sides of proximate gripping members and connected to being spaced from the cam surface to provide clearances into which the struts may fold, with V the angularity between opposite bases of each strut forming means for causing the chordal pressure exerted upon the struts by inward movement of the gripping members to have only cutward lateral components.

4. A collet for a chuck having an internal conical cam surface, said collet comprising a plurality of tapered angularly spaced rigid gripping members symmetrically disposed about the axis of the cam surface, said gripping members being arranged to extend to and be engaged by the cam surface and being movable radially in concert toward and away from said axis whereby the volume of the spaces between them is varied, with adjacent sides of proximate gripping members forming outwardly flaring angles to one another, struts of non compressible resilient material in said spaces based upon said adjacent sides of proximate gripping members and connected to said members, the outer surfaces of said struts being spaced from the cam surface to provide clearances into which the struts may'fold, with the angularity between the opposite bases of each strut forming means for causing an out-' ward lateral pressure to be exerted upon the struts by inward movement of the gripping members in excess of the inward lateral pressure thereon, whereby the struts are folded outwardly toward the cam surface when the gripping members are moved radially inwardly.

5. A collet of wide range for a machine tool chuck having an internal conical cam surface, said collet comprising a plurality of tapered angularly spaced rigid gripping members symmetrically disposed about the axis of the cam surface and being arranged to extend to and be engaged by the cam surface and being movable radially in concert toward and away from said.

axis, whereby the volume of the spaces between them is varied, non-compressible non-metallic struts of resilient material in said spaces based bers and connected to said members, the outer surfaces of said struts being spaced from the cam surface to provide clearances into which the struts may fold, and means including the struts for inducing outward folding of said struts upon axial loading thereof, said struts being arranged in substantially chordal relation to said axis when not subjected to pressure. p

6. A collet of wide range for a machine tool chuck having an internal conical cam surface, said collet comprising a plurality of tapered angularly spaced rigid gripping members symmetrically disposed about the axis of the cam surface and being arranged to extend to and be engaged by the cam surface and being movable radially in concert toward and away from said axis, whereby the volume of the spaces between them is varied, non-compressible non-metallic struts of resilient material in said spaces based upon adjacent sides of proximate gripping members and connected to said members, said struts being of less radial extent than the gripping members with their outer surfaces spaced radially from the inner and outer surfaces of the gripping members to provide clearances into which the struts may fold, the medial portions of the struts in planes transverse to the axis of the cam surface being displaced radially from planes through the centers of pressure imposed upon the bases of the gripping members by the inward. radial movement of said gripping members, and means including the struts for inducing folding of said struts upon axial loading thereof. 7

'7. A collet of wide range for a machine tool 'chuck having an internal conical cam surface,

- upon adjacentfsides of proximate gripping memmembers with their oute surfaces spaced radially 7 from the inner and outer surfaces of the gripping members to provide clearances into which the struts may fold, the medial portions of the struts in planes transverse to the axis of the cam surface being displaced radially outwardly from planes through the centers of pressure imposed upon the bases of the gripping members by the inward radial movement of said gripping members, and means including the struts for inducing outward folding of said struts upon axial loading thereof.

ARTHUR MERE-10K STONER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,923,283 Stokes -Aug. 22, 1933 2,346,706 Stoner Apr. 18, 1944 

